@article{BanerjeeSaalfrank2014, author = {Banerjee, Shiladitya and Saalfrank, Peter}, title = {Vibrationally resolved absorption, emission and resonance Raman spectra of diamondoids: a study based on time-dependent correlation functions}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {1}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c3cp53535e}, pages = {144 -- 158}, year = {2014}, language = {en} } @article{MondalBhuniaDemeshkoetal.2014, author = {Mondal, Suvendu Sekhar and Bhunia, Asamanjoy and Demeshko, Serhiy and Kelling, Alexandra and Schilde, Uwe and Janiak, Christoph and Holdt, Hans-J{\"u}rgen}, title = {Synthesis of a Co(II)-imidazolate framework from an anionic linker precursor: gas-sorption and magnetic properties}, series = {CrystEngComm}, volume = {16}, journal = {CrystEngComm}, number = {1}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1466-8033}, doi = {10.1039/c3ce42040j}, pages = {39 -- 42}, year = {2014}, abstract = {A Co(II)-imidazolate-4-amide-5-imidate based MOF, IFP-5, is synthesized by using an imidazolate anion-based novel ionic liquid as a linker precursor under solvothermal conditions. IFP-5 shows significant amounts of gas (N-2, CO2, CH4 and H-2) uptake capacities. IFP-5 exhibits an independent high spin Co(II) centre and antiferromagnetic coupling.}, language = {en} } @article{KopyraKellerBald2014, author = {Kopyra, Janina and Keller, A. and Bald, Ilko}, title = {On the role of fluoro-substituted nucleosides in DNA radiosensitization for tumor radiation therapy}, series = {RSC Advances}, volume = {4}, journal = {RSC Advances}, number = {13}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2046-2069}, doi = {10.1039/c3ra46735j}, pages = {6825 -- 6829}, year = {2014}, language = {en} } @article{SchoenbornHartke2014, author = {Sch{\"o}nborn, Jan Boyke and Hartke, Bernd}, title = {Photochemical dynamics of E-methylfurylfulgide-kinematic effects on photorelaxation dynamics of furylfulgides}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {6}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c3cp53495b}, pages = {2483 -- 2490}, year = {2014}, abstract = {With the present theoretical study of the photochemical switching of E-methylfurylfulgide we contribute an important step towards the understanding of the photochemical processes in furylfulgide-related molecules. We have carried out large-scale, full-dimensional direct semiempirical configuration-interaction surface-hopping dynamics of the photoinduced ring-closure reaction. Simulated static and dynamical UV/Vis-spectra show good agreement with experimental data of the same molecule. By a careful investigation of our dynamical data, we were able to identify marked differences to the dynamics of the previously studied E-isopropylfurylfulgide. With our simulations we can not only reproduce the experimentally observed quantum yield differences qualitatively but we can also pinpoint two reasons for them: kinematics and pre-orientation. With our analysis, we thus offer straightforward molecular explanations for the high sensitivity of the photodynamics towards seemingly minor changes in molecular constitution. Beyond the realm of furylfulgides, these insights provide additional guidance to the rational design of photochemically switchable molecules.}, language = {en} } @article{GhobadiHeuchelKratzetal.2014, author = {Ghobadi, Ehsan and Heuchel, Matthias and Kratz, Karl and Lendlein, Andreas}, title = {Atomistic simulation of the shape-memory effect in dry and water swollen Poly[(rac-lactide)-co-glycolide] and copolyester urethanes thereof}, series = {Macromolecular chemistry and physics}, volume = {215}, journal = {Macromolecular chemistry and physics}, number = {1}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1352}, doi = {10.1002/macp.201300507}, pages = {65 -- 75}, year = {2014}, abstract = {An atomistic molecular dynamics simulation approach is applied to model the influence of urethane linker units as well as the addition of water molecules on the simulated shape-memory properties of poly[(rac-lactide)-co-glycolide] (PLGA) and PLGA-based copolyester urethanes comprising different urethane linkers. The shape-memory performance of these amorphous packing models is explored in a simulated heating-deformation-cooling-heating procedure. Depending on the type of incorporated urethane linker, the mechanical properties of the dry copolyester urethanes are found to be significantly improved compared with PLGA, which can be attributed to the number of intermolecular hydrogen bonds between the urethane units. Good shape-memory properties are observed for all the modeled systems. In the dry state, the shape fixation is found to be improved by implementation of urethane units. After swelling of the copolymer models with water, which results in a reduction of their glass transition temperatures, the relaxation kinetics during unloading and shape recovery are found to be substantially accelerated.}, language = {en} } @article{WinterThielZabeletal.2014, author = {Winter, Alette and Thiel, Kerstin and Zabel, Andre and Klamroth, Tillmann and Poeppl, Andreas and Kelling, Alexandra and Schilde, Uwe and Taubert, Andreas and Strauch, Peter}, title = {Tetrahalidocuprates(II) - structure and EPR spectroscopy. Part 2: tetrachloridocuprates(II)}, series = {New journal of chemistry}, volume = {38}, journal = {New journal of chemistry}, number = {3}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1144-0546}, doi = {10.1039/c3nj01039b}, pages = {1019 -- 1030}, year = {2014}, abstract = {We present and discuss the results of crystallographic and electron paramagnetic resonance (EPR) spectroscopic analyses of five tetrachloridocuprate(II) complexes to supply a useful tool for the structural characterisation of the [CuCl4](2-) moiety in the liquid state, for example in ionic liquids, or in solution. Bis(benzyltriethylammonium)-, bis(trimethylphenylammonium)-, bis(ethyltriphenylphosphonium)-, bis(benzyltriphenylphosphonium)-, and bis(tetraphenylarsonium) tetrachloridocuprate(II) were synthesised and characterised by elemental, IR, EPR and X-ray analyses. The results of the crystallographic analyses show distorted tetrahedral coordination geometry of all [CuCl4](2-) anions in the five complexes and prove that all investigated complexes are stabilised by hydrogen bonds of different intensities. Despite the use of sterically demanding ammonium, phosphonium and arsonium cations to obtain the separation of the paramagnetic Cu(II) centres for EPR spectroscopy no hyperfine structure was observed in the EPR spectra but the principal values of the electron Zeeman tensor, g(parallel to) and g(perpendicular to), could be determined. With these EPR data and the crystallographic parameters we were able to carry out a correlation study to anticipate the structural situation of tetrachloridocuprates in different physical states. This correlation is in good agreement with DFT calculations.}, language = {en} } @article{DiFlorioBruendermannYadavallietal.2014, author = {Di Florio, Giuseppe and Bruendermann, Erik and Yadavalli, Nataraja Sekhar and Santer, Svetlana and Havenith, Martina}, title = {Polarized 3D Raman and nanoscale near-field optical microscopy of optically inscribed surface relief gratings: chromophore orientation in azo-doped polymer films}, series = {Soft matter}, volume = {10}, journal = {Soft matter}, number = {10}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1744-683X}, doi = {10.1039/c3sm51787j}, pages = {1544 -- 1554}, year = {2014}, abstract = {We have used polarized confocal Raman microspectroscopy and scanning near-field optical microscopy with a resolution of 60 nm to characterize photoinscribed grating structures of azobenzene doped polymer films on a glass support. Polarized Raman microscopy allowed determining the reorientation of the chromophores as a function of the grating phase and penetration depth of the inscribing laser in three dimensions. We found periodic patterns, which are not restricted to the surface alone, but appear also well below the surface in the bulk of the material. Near-field optical microscopy with nanoscale resolution revealed lateral two-dimensional optical contrast, which is not observable by atomic force and Raman microscopy.}, language = {en} } @article{KopecLapokLaschewskyetal.2014, author = {Kopec, Maciej and Lapok, Lukasz and Laschewsky, Andr{\´e} and Zapotoczny, Szczepan and Nowakowska, Maria}, title = {Polyelectrolyte multilayers with perfluorinated phthalocyanine selectively entrapped inside the perfluorinated nanocompartments}, series = {Soft matter}, volume = {10}, journal = {Soft matter}, number = {10}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1744-683X}, doi = {10.1039/c2sm26938d}, pages = {1481 -- 1488}, year = {2014}, abstract = {A novel perfluorinated magnesium phthalocyanine (MgPcF64) was synthesized and employed to probe nanodomains in hydrophobically modified, amphiphilic cationic polyelectrolytes bearing alkyl and/or fluoroalkyl side chains. MgPcF64 was found to be solubilized exclusively in the aqueous solutions of the fluorocarbon modified polycations, occupying the perfluorinated nanocompartments provided, while analogous polyelectrolytes with alkyl side chains forming hydrocarbon nanocompartments could not host the MgPcF64 dye. Multilayer films were fabricated by means of the layer-by-layer (LbL) deposition method using sodium poly(styrene sulfonate) as a polyanion. Linear multilayer growth was confirmed by UV-Vis spectroscopy and spectroscopic ellipsometry. Atomic force microscopy studies indicated that the micellar conformation of the polycations is preserved in the multilayer films. Fluorescence spectroscopy measurements confirmed that MgPcF64 stays embedded inside the fluorocarbon domains after the deposition process. This facile way of selectively incorporating water-insoluble, photoactive molecules into the structure of polyelectrolyte multilayers may be utilized for nanoengineering of ultrathin film-based optoelectronic devices.}, language = {en} } @article{ErmeydanCabaneGierlingeretal.2014, author = {Ermeydan, Mahmut Ali and Cabane, Etienne and Gierlinger, Notburga and Koetz, Joachim and Burgert, Ingo}, title = {Improvement of wood material properties via in situ polymerization of styrene into tosylated cell walls}, series = {RSC Advances}, volume = {4}, journal = {RSC Advances}, number = {25}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2046-2069}, doi = {10.1039/c4ra00741g}, pages = {12981 -- 12988}, year = {2014}, abstract = {As an engineering material derived from renewable resources, wood possesses excellent mechanical properties in view of its light weight but also has some disadvantages such as low dimensional stability upon moisture changes and low durability against biological attack. Polymerization of hydrophobic monomers in the cell wall is one of the potential approaches to improve the dimensional stability of wood. A major challenge is to insert hydrophobic monomers into the hydrophilic environment of the cell walls, without increasing the bulk density of the material due to lumen filling. Here, we report on an innovative and simple method to insert styrene monomers into tosylated cell walls (i.e. -OH groups from natural wood polymers are reacted with tosyl chloride) and carry out free radical polymerization under relatively mild conditions, generating low wood weight gains. In-depth SEM and confocal Raman microscopy analysis are applied to reveal the distribution of the polystyrene in the cell walls and the lumen. The embedding of polystyrene in wood results in reduced water uptake by the wood cell walls, a significant increase in dimensional stability, as well as slightly improved mechanical properties measured by nanoindentation.}, language = {en} } @article{FudickarLinker2014, author = {Fudickar, Werner and Linker, Torsten}, title = {Intermediates in the formation and thermolysis of peroxides from oxidations with singlet oxygen}, series = {Australian journal of chemistry}, volume = {67}, journal = {Australian journal of chemistry}, number = {3}, publisher = {CSIRO}, address = {Clayton}, issn = {0004-9425}, doi = {10.1071/CH13423}, pages = {320 -- 327}, year = {2014}, abstract = {Herein we describe the recent mechanistic understandings of the singlet oxygen ene reaction to give hydroperoxides and the [4+2] cycloaddition affording endoperoxides. Both experimental findings and theoretical work conclude in the formation of intermediates structurally similar to perepoxides during the ene reaction. Such intermediates mainly control the regio- and stereoselectivities of this reaction class. For the [4+2] cycloaddition, both a synchronous concerted reaction (benzene, naphthalenes) and a stepwise reaction with a non-symmetric zwitterionic intermediate (larger acenes) have been found. The thermolysis of endoperoxides derived from acenes proceeds stepwise for anthracenes, but in a concerted manner for less stable adducts such as naphthalene.}, language = {en} } @article{BauerGodecMetzler2014, author = {Bauer, Maximilian and Godec, Aljaz and Metzler, Ralf}, title = {Diffusion of finite-size particles in two-dimensional channels with random wall configurations}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {13}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c3cp55160a}, pages = {6118 -- 6128}, year = {2014}, abstract = {Diffusion of chemicals or tracer molecules through complex systems containing irregularly shaped channels is important in many applications. Most theoretical studies based on the famed Fick-Jacobs equation focus on the idealised case of infinitely small particles and reflecting boundaries. In this study we use numerical simulations to consider the transport of finite-size particles through asymmetrical two-dimensional channels. Additionally, we examine transient binding of the molecules to the channel walls by applying sticky boundary conditions. We consider an ensemble of particles diffusing in independent channels, which are characterised by common structural parameters. We compare our results for the long-time effective diffusion coefficient with a recent theoretical formula obtained by Dagdug and Pineda}, language = {en} } @article{CywinskiNonoCharbonniereetal.2014, author = {Cywinski, Piotr J. and Nono, Katia Nchimi and Charbonniere, Loic J. and Hammann, Tommy and L{\"o}hmannsr{\"o}ben, Hans-Gerd}, title = {Photophysical evaluation of a new functional terbium complex in FRET-based time-resolved homogenous fluoroassays}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {13}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c3cp54883j}, pages = {6060 -- 6067}, year = {2014}, abstract = {A new functional luminescent lanthanide complex (LLC) has been synthesized with terbium as a central lanthanide ion and biotin as a functional moiety. Unlike in typical lanthanide complexes assembled via carboxylic moieties, in the presented complex, four phosphate groups are chelating the central lanthanide ion. This special chemical assembly enhances the complex stability in phosphate buffers conventionally used in biochemistry. The complex synthesis strategy and photophysical properties are described as well as the performance in time-resolved Forster Resonance Energy Transfer (FRET) assays. In those assays, this biotin-LLC transferred energy either to acceptor organic dyes (Cy5 or AF680) labelled on streptavidin or to quantum dots (QD655 or QD705) surfacefunctionalised with streptavidins. The permanent spatial donor-acceptor proximity is assured through strong and stable biotin-streptavidin binding. The energy transfer is evidenced from the quenching observed in donor emission and from a decrease in donor luminescence decay, both associated with simultaneous increase in acceptor intensity and in the decay time. The dye-based assays are realised in TRIS and in PBS, whereas QD-based systems are studied in borate buffer. The delayed emission analysis allows for quantifying the recognition process and for auto-fluorescence-free detection, which is particularly relevant for application in bioanalysis. In accordance with Forster theory, Forsterradii (R0) were found to be around 60 angstrom for organic dyes and around 105 angstrom for QDs. The FRET efficiency (Z) reached 80\% and 25\% for dye and QD acceptors, respectively. Physical donor-acceptor distances (r) have been determined in the range 45-60 angstrom for organic dye acceptors, while for acceptor QDs between 120 angstrom and 145 angstrom. This newly synthesised biotin-LLC extends the class of highly sensitive analytical tools to be applied in the bioanalytical methods such as time-resolved fluoroimmunoassays (TR-FIA), luminescent imaging and biosensing.}, language = {en} } @article{MondalBhuniaKellingetal.2014, author = {Mondal, Suvendu Sekhar and Bhunia, Asamanjoy and Kelling, Alexandra and Schilde, Uwe and Janiak, Christoph and Holdt, Hans-J{\"u}rgen}, title = {A supramolecular Co(II)(14)- metal-organic cube in a hydrogen-bonded network and a Co(II)-organic framework with a flexible methoxy substituent}, series = {Chemical communications}, volume = {50}, journal = {Chemical communications}, number = {41}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1359-7345}, doi = {10.1039/c3cc49698h}, pages = {5441 -- 5443}, year = {2014}, abstract = {The reaction of 4,5-dicyano-2-methoxyimidazole (L1) with Co(NO3)(2.) 6H(2)O under solvothermal conditions in DMF, a MOF, IFP-8 and a hydrogen-bonded network consisting of tetradecanuclear Co(II)(14)-metal organic cube (1) are achieved. 1 shows the bcu net with 14 cobalt atoms.}, language = {en} } @article{SangoroIacobAgapovetal.2014, author = {Sangoro, Joshia R. and Iacob, C. and Agapov, A. L. and Wang, Yangyang and Berdzinski, Stefan and Rexhausen, Hans and Strehmel, Veronika and Friedrich, C. and Sokolov, A. P. and Kremer, F.}, title = {Decoupling of ionic conductivity from structural dynamics in polymerized ionic liquids}, series = {Soft matter}, volume = {10}, journal = {Soft matter}, number = {20}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1744-683X}, doi = {10.1039/c3sm53202j}, pages = {3536 -- 3540}, year = {2014}, abstract = {Charge transport and structural dynamics in low molecular weight and polymerized 1-vinyl-3-pentylimidazolium bis(trifluoromethylsulfonyl) imide ionic liquids (ILs) are investigated by a combination of broadband dielectric spectroscopy, dynamic mechanical spectroscopy and differential scanning calorimetry. While the dc conductivity and fluidity exhibit practically identical temperature dependence for the non-polymerized IL, a significant decoupling of ionic conduction from structural dynamics is observed for the polymerized IL. In addition, the dc conductivity of the polymerized IL exceeds that of its molecular counterpart by four orders of magnitude at their respective calorimetric glass transition temperatures. This is attributed to the unusually high mobility of the anions especially at lower temperatures when the structural dynamics is significantly slowed down. A simple physical explanation of the possible origin of the remarkable decoupling of ionic conductivity from structural dynamics is proposed.}, language = {en} } @article{SarauliXuDietzeletal.2014, author = {Sarauli, David and Xu, Chenggang and Dietzel, Birgit and Schulz, Burkhard and Lisdat, Fred}, title = {A multilayered sulfonated polyaniline network with entrapped pyrroloquinoline quinone-dependent glucose dehydrogenase: tunable direct bioelectrocatalysis}, series = {Journal of materials chemistry : B, Materials for biology and medicine}, volume = {2}, journal = {Journal of materials chemistry : B, Materials for biology and medicine}, number = {21}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2050-750X}, doi = {10.1039/c4tb00336e}, pages = {3196 -- 3203}, year = {2014}, abstract = {A feasible approach to construct multilayer films of sulfonated polyanilines - PMSA1 and PABMSA1 containing different ratios of aniline, 2-methoxyaniline-5-sulfonic acid (MAS) and 3-aminobenzoic acid (AB), with the entrapped redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) on Au and ITO electrode surfaces, is described. The formation of layers has been followed and confirmed by electrochemical impedance spectroscopy (EIS), which demonstrates that the multilayer assembly can be achieved in a progressive and uniform manner. The gold and ITO electrodes subsequently modified with PMSA1:PQQ-GDH and PABMSA1 films are studied by cyclic voltammetry (CV) and UV-Vis spectroscopy which show a significant direct bioelectrocatalytical response to the oxidation of the substrate glucose without any additional mediator. This response correlates linearly with the number of deposited layers. Furthermore, the constructed polymer/enzyme multilayer system exhibits a rather good long-term stability, since the catalytic current response is maintained for more than 60\% of the initial value even after two weeks of storage. This verifies that a productive interaction of the enzyme embedded in the film of substituted polyaniline can be used as a basis for the construction of bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction.}, language = {en} } @article{ErmeydanCabaneHassetal.2014, author = {Ermeydan, Mahmut Ali and Cabane, Etienne and Hass, Philipp and Koetz, Joachim and Burgert, Ingo}, title = {Fully biodegradable modification of wood for improvement of dimensional stability and water absorption properties by poly(epsilon-caprolactone) grafting into the cell walls}, series = {Green chemistry : an international journal and green chemistry resource}, volume = {16}, journal = {Green chemistry : an international journal and green chemistry resource}, number = {6}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9262}, doi = {10.1039/c4gc00194j}, pages = {3313 -- 3321}, year = {2014}, abstract = {Materials derived from renewable resources are highly desirable in view of more sustainable manufacturing. Among the available natural materials, wood is one of the key candidates, because of its excellent mechanical properties. However, wood and wood-based materials in engineering applications suffer from various restraints, such as dimensional instability upon humidity changes. Several wood modification treatments increase water repellence, but the insertion of hydrophobic polymers can result in a composite material which cannot be considered as renewable anymore. In this study, we report on the grafting of the fully biodegradable poly(epsilon-caprolactone) (PCL) inside the wood cell walls by Sn(Oct)(2) catalysed ring-opening polymerization (ROP). The presence of polyester chains within the wood cell wall structure is monitored by confocal Raman imaging and spectroscopy as well as scanning electron microscopy. Physical tests reveal that the modified wood is more hydrophobic due to the bulking of the cell wall structure with the polyester chains, which results in a novel fully biodegradable wood material with improved dimensional stability.}, language = {en} } @article{NeffevonRuestenLangeBrauneetal.2014, author = {Neffe, Axel T. and von R{\"u}sten-Lange, Maik and Braune, Steffen and L{\"u}tzow, Karola and Roch, Toralf and Richau, Klaus and Kr{\"u}ger, Anne and Becherer, Tobias and Th{\"u}nemann, Andreas F. and Jung, Friedrich and Haag, Rainer and Lendlein, Andreas}, title = {Multivalent grafting of hyperbranched oligo- and polyglycerols shielding rough membranes to mediate hemocompatibility}, series = {Journal of materials chemistry : B, Materials for biology and medicine}, volume = {2}, journal = {Journal of materials chemistry : B, Materials for biology and medicine}, number = {23}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2050-750X}, doi = {10.1039/c4tb00184b}, pages = {3626 -- 3635}, year = {2014}, abstract = {Hemocompatible materials are needed for internal and extracorporeal biomedical applications, which should be realizable by reducing protein and thrombocyte adhesion to such materials. Polyethers have been demonstrated to be highly efficient in this respect on smooth surfaces. Here, we investigate the grafting of oligo- and polyglycerols to rough poly(ether imide) membranes as a polymer relevant to biomedical applications and show the reduction of protein and thrombocyte adhesion as well as thrombocyte activation. It could be demonstrated that, by performing surface grafting with oligo-and polyglycerols of relatively high polydispersity (>1.5) and several reactive groups for surface anchoring, full surface shielding can be reached, which leads to reduced protein adsorption of albumin and fibrinogen. In addition, adherent thrombocytes were not activated. This could be clearly shown by immunostaining adherent proteins and analyzing the thrombocyte covered area. The presented work provides an important strategy for the development of application relevant hemocompatible 3D structured materials.}, language = {en} } @article{PlehnMegowMay2014, author = {Plehn, Thomas and Megow, J{\"o}rg and May, Volkhard}, title = {Concerted charge and energy transfer processes in a highly flexible fullerene-dye system: a mixed quantum-classical study}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {25}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c4cp01081g}, pages = {12949 -- 12958}, year = {2014}, abstract = {Photoinduced excitation energy transfer and accompanying charge separation are elucidated for a supramolecular system of a single fullerene covalently linked to six pyropheophorbide-a dye molecules. Molecular dynamics simulations are performed to gain an atomistic picture of the architecture and the surrounding solvent. Excitation energy transfer among the dye molecules and electron transfer from the excited dyes to the fullerene are described by a mixed quantum-classical version of the Forster rate and the semiclassical Marcus rate, respectively. The mean characteristic time of energy redistribution lies in the range of 10 ps, while electron transfer proceeds within 150 ps. In between, on a 20 to 50 ps time-scale, conformational changes take place in the system. This temporal hierarchy of processes guarantees efficient charge separation, if the structure is exposed to a solvent. The fast energy transfer can adopt the dye excitation to the actual conformation. In this sense, the probability to achieve charge separation is large enough since any dominance of unfavorable conformations that exhibit a large dye-fullerene distance is circumvented. And the slow electron transfer may realize an averaging with respect to different conformations. To confirm the reliability of our computations, ensemble measurements on the charge separation dynamics are simulated and a very good agreement with the experimental data is obtained.}, language = {en} } @article{GrunzelPilarekSteinbruecketal.2014, author = {Grunzel, Petra and Pilarek, Maciej and Steinbrueck, Doerte and Neubauer, Antje and Brand, Eva and Kumke, Michael Uwe and Neubauer, Peter and Krause, Mirja}, title = {Mini-scale cultivation method enables expeditious plasmid production in Escherichia coli}, series = {Biotechnology journal : systems \& synthetic biology, nanobiotech, medicine}, volume = {9}, journal = {Biotechnology journal : systems \& synthetic biology, nanobiotech, medicine}, number = {1}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1860-6768}, doi = {10.1002/biot.201300177}, pages = {128 -- 136}, year = {2014}, abstract = {The standard procedure in the lab for plasmid isolation usually involves a 2-mL, 16 h over-night cultivation in 15-mL bioreaction tubes in LB medium. This is time consuming, and not suitable for high-throughput applications. This study shows that it is possible to produce plasmid DNA (pDNA) in a 1.5-mL microcentrifuge tube with only 100 L cultivation volume in less than 7 h with a simple protocol. Compared with the standard LB cultivation for pDNA production reaching a final pDNA concentration range of 1.5-4 mu g mL(-1), a 6- to 10-fold increase in plasmid concentration (from 10 up to 25 mu g mL(-1) cultivation volume) is achieved using an optimized medium with an internal substrate delivery system (EnBase (R)). Different strains, plasmids, and the applicability of different inoculation tools (i.e. different starting ODs) were compared, demonstrating the robustness of the system. Additionally, dissolved oxygen was monitored in real time online, indicating that under optimized conditions oxygen limitation can be avoided. We developed a simple protocol with a significantly decreased procedure time, enabling simultaneous handling of more samples, while a consistent quality and a higher final pDNA concentration are ensured.}, language = {en} } @article{EhlertUngerSaalfrank2014, author = {Ehlert, Christopher and Unger, Wolfgang E. S. and Saalfrank, Peter}, title = {C K-edge NEXAFS spectra of graphene with physical and chemical defects: a study based on density functional theory}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {27}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c4cp01106f}, pages = {14083 -- 14095}, year = {2014}, abstract = {Recently, C K-edge Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra of graphite (HOPG) surfaces have been measured for the pristine material, and for HOPG treated with either bromine or krypton plasmas (Lippitz et al., Surf. Sci., 2013, 611, L1). Changes of the NEXAFS spectra characteristic for physical (krypton) and/or chemical/physical modifications of the surface (bromine) upon plasma treatment were observed. Their molecular origin, however, remained elusive. In this work we study by density functional theory, the effects of selected point and line defects as well as chemical modifications on NEXAFS carbon K-edge spectra of single graphene layers. For Br-treated surfaces, also Br 3d X-ray Photoelectron Spectra (XPS) are simulated by a cluster approach, to identify possible chemical modifications. We observe that some of the defects related to plasma treatment lead to characteristic changes of NEXAFS spectra, similar to those in experiment. Theory provides possible microscopic origins for these changes.}, language = {en} }